Pilonidal disease is a common skin condition. It usually develops near the top of the crease between the buttocks.

What causes pilonidal disease isn't clear. It may start when loose hair and other skin debris get trapped in the skin, creating a cyst. If the cyst becomes infected, it may form a pocket of pus, called an abscess.

Treatment may include draining the cyst and sometimes having surgery to remove the cyst if it does not clear up on its own.